Fluorination of acetals, ketals and orthoesters

ABSTRACT

This invention pertains to perfluoropolyethers and perhalogenated chlorofluoroether polymers that can be prepared by fluorinating polymers made by the polymerization of acetals, ketals, polyacetals, polyketals and orthoesters with elemental fluorine.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 07/250,384, filed Sept. 28, 1988, the teachings of which areincorporated by reference herein.

BACKGROUND

Perfluoropolyethers are highly regarded in the specialty lubricant fieldbecause of their wide liquid ranges, low vapor pressures and highthermal and oxidative stabilities. Because of these properties (many ofwhich are unique to fluorocarbons), they are excellent high performancelubricants, superior base stocks for greases, excellent lubricatingoils, and heat transfer fluids. In addition, because of these uniquelyoutstanding properties, saturated perfluoropolyethers are of currentinterest as specialty sealants, elastomers and plastics.

In spite of their unlimited potential, only three perfluoropolyethersare commercially available to date because of the lack of fluorocarbonsintermediates which are suitable for preparing the polymers. They are:

1. DuPont's Krytox™ fluid which is made by polymerizinghexafluoropropylene oxide.

2. Demnum™ fluid, a product of Daikin Industries, is obtained by ringopening polymerization of 2,2,3,3-tetrafluorooxetane using a catalystwith subsequent treatment of the highly fluorinated polyether withfluorine gas to give a perfluorinated product.

3. Montedison's Fomblin Z™ and Fomblin Y™ fluids which are prepared byphotooxidizing tetrafluoroethylene and hexafluoropropylene oxide,respectively, in the presence of oxygen.

A process has been described for preparing perfluoropolyethers byreaction of a hydrocarbon polyether with elemental fluorine in thepresence of a hydrogen fluoride scavenger. See U.S. Pat. No. 4,755,567.

SUMMARY OF THE INVENTION

This invention relates to perfluoropolyether and perhalogenatedchlorofluoroether polymers that can be prepared by fluorinating polymersmade by the polymerization of acetals, ketals, polyacetals, polyketalsand orthoesters with elemental fluorine. The products formed by thepresent invention have essentially the following formula: ##STR1##wherein Y and Y' are the same or different and are selected from thegroup consisting of linear and branched perfluoroalkylenes having atleast 2 carbon atoms; perfluoroalkyleneoxyalkylene andperfluoropoly(alkyleneoxyalkylene) each having alkylene groupscontaining at least two carbon atoms wherein in Y or Y' one or more ofthe fluorine atoms may be substituted by a halogen atom other thanfluorine; wherein X and Z are the same or different and are selectedfrom the group consisting of --(CF₂)_(r) COF, --(CF₂)_(r) OCF₃,--(CF₂)_(r) COOH and C_(r) F_(2r+1-q) Cl_(q), wherein r is an integerfrom 1 to 12 and q is an integer from 0 to 25; wherein R₁, R₂, R₃ and R₄are the same or different and are selected from the group consisting of--F, --Cl, --CF₂ Cl, --CFCl₂, --CCl₃, perfluoroalkyl of one to tencarbon atoms and perfluoroalkoxyalkyl of one to ten carbon atoms whereinone or more of the fluorine atoms may be substituted by a halogen atomother than fluorine; wherein n is an integer from 2 to 1,000; andwherein m is an integer from 0 to 1,000; provided that when R₁, R₂, R₃and R₄ together are F then Y or Y' comprises an ethylene group having atleast one fluorine atom which is substituted by a halogen other thanfluorine.

This invention also relates to perhalogenated polyethers of the formula:##STR2## wherein R₁, R₂, X and Z are defined above and n is an integerfrom 2 to 1000; provided that R₁ and R₂ cannot both be fluorine atoms.

The perfluoropolyethers and the perhalogenated chlorofluoropolyethers ofthis invention can be used as lubricants, hydraulic fluids, thermalshock fluids, vapor phase soldering fluids and in numerous otherapplications in which an inert, nonflammable, oxidatively stable fluidis required. The low molecular weight perfluoropolyethers of the presentinvention have many useful applications in the electronics industry.

DETAILED DESCRIPTION OF THE INVENTION

In general, the perfluoropolyether and perhalogenatedchlorofluoropolyether polymers have the formula: ##STR3## wherein Y andY' are the same or different and are selected from the group consistingof linear and branched perfluoroalkylenes having at least 2 carbonatoms, preferably having 2 to 6 carbon atoms;Perfluoroalkyleneoxyalkylene and perfluoropoly(alkyleneoxyalkylene) eachhaving alkylene groups containing at least two carbon atoms, preferablyhaving from 2 to 30 carbons and most preferably having 4 to 8 carbons;wherein in Y or Y' one or more of the fluorine atoms may be substitutedby a halogen atom other than fluorine. Y and Y' can be isotacticperfluoropolyethers or atactic perfluoropolyethers, such as --CF₂ CF₂CF₂, --CF₂ CF₂ CF₂ CF₂ --, --CF₂ CF₂ OCF₂ CF₂ --, --CF₂(CF₃)CFOCF(CF₃)CF₂ -- and --CF₂ CF₂ OCF₂ CF₂ OCF₂ CF₂ --. X and Z arethe same or different and are selected from the group consisting of--(CF₂)_(r) COF, --(CF₂)_(r) OCF₃, --(CF₂)_(r) COOH and C_(r) F_(2r+1-q)Cl_(q), wherein r is an integer from 1 to 12 and q is an integer from 0to 25. R₁, R₂, R₃ and R₄ are the same or different and are selected fromthe group consisting of --F, --Cl, --CF₂ Cl, --CFCl₂, --CCl₃,perfluoroalkyl of one to ten carbon atoms, such as --CF.sub. 3, --C₂ F₅,--C₃ F₇ and --C₄ F₉ and perfluoroalkoxyalkyl of one to ten carbon atoms,such as --OCF₃ and --OCF₅, wherein one or more of the fluorine atoms insaid perfluoroalkyl and perfluoroalkoxyalkyl may be substituted by ahalogen atom other than fluorine. Preferably R₁ to R₄ are F and --CF₃groups. n is an integer from 2 to 1,000; and m is an integer from 0 to1,000; provided that when R₁, R₂, R₃ and R₄ together are F then Y or Y'comprises an ethylene group having at least one fluorine atom which issubstituted with a halogen atom other than fluorine, preferably bychlorine.

The n and m subscripts of formula I are average indices of compositionsuch that when m is zero the polyether is referred to as an alternatingcopolymer of ##STR4## When m and n are greater than zero, the polyetheris a terpolymer containing ##STR5## groups having random OY and OY'units along the polymer chain. The simplest member of this class ofcompounds is a 1:1 copolymer of difluoromethylene oxide andtetrafluoroethylene oxide which is the subject of U.S. Pat. No.4,760,198.

This invention also relates to perfluoropolyethers and perhalogenatedchlorofluoropolyethers of Formula I where Y and Y' are polyethers andhave the average formula: ##STR6## wherein R₁, R₂, R₃, R₄, R₅ and R₆ arethe same or different and are selected from the group consisting of --F,--Cl, --CF₂ Cl, --CFCl₂, --CCl₃, perfluoroalkyl of one to ten carbonatoms and perfluoroalkoxyalkyl of one to ten carbon atoms wherein one ormore of the fluorine atoms may be substituted by a halogen atom otherthan fluorine; wherein X and Z are the same or different and areselected from the group consisting of --(CF₂)_(r) COF, --(CF₂)_(r) OCF₃,--(CF₂)_(r) COOH and C_(r) F_(2r+1-q) Cl_(q) wherein r is an integerfrom 1 to twelve and q is an integer from 0 to 25; wherein n is aninteger from 2 to 1000, m is an integer from 0 to 1000; and p and t arethe same or different and are integers from 1 to 50, provided that whenp and t are one and R₁, R₂, R₃ and R₄ together are fluorine, then R₅ orR₆ is a group other than fluorine. Preferably, p and t are integers from1 to 10.

Examples of perfluoropolyethers where m in formula I is zero and p is aninteger between 2 and are shown below: ##STR7##

Examples of perfluorinated polyethers of formula I where m is zero, p isdefined above and Y is an isotactic perfluoropolyether or atacticperfluoropolyether are: ##STR8##

Examples of random copolymers of formula I in which m and n are greaterthan zero, and p is defined above, include: ##STR9##

Perfluoropolyethers and perhalogenated chlorofluoropolyethers can alsobe prepared which have the average formula: ##STR10## wherein X isselected from the group consisting of --(CF₂)_(r) COOH, --(CF₂)_(r)OCF₃, --(CF₂)_(r) COF, and C_(r) F_(2r+1-q) Cl_(q) where r is an integerfrom 1 to 12 and q is an integer from 0 to 25. Preferably X is --CF₃,--C₂ F₅, --CF₂ COOH, --CF₂ OCF₃ and CF₂ COF; wherein n is an integerfrom 1 to 50; and wherein R is selected from the group consisting of--F, --CF₂ Cl, --CFCl₂, CCl₃ and perfluoroalkyl of one to ten carbons.

This invention further pertains to perfluoropolyethers andperhalogenated chlorofluoropolyethers having the average formula:##STR11## wherein R₁, R₂, X and Z are defined above, and n is an integerfrom 2 to 1000; provided that R₁ and R₂ cannot both be fluorine atoms.

This invention further pertains to a method of making perhalogenatedformal, acetal, ketal and orthocarbonate compounds andperfluoropolyether and perhalogenated chlorofluoropolyether polymersthereof. The compounds are made by fluorination of acetal, ketal, formalor orthocarbonate hydrocarbon precursors.

The reaction of a diol with either an aldehyde, acetal, ketal ortrialkyl orthoesters can be used to give a polyether if the startingmaterials and reaction conditions are carefully chosen. For example, ifan aldehyde such as formaldehyde, acetaldehyde or butyraldehyde isreacted with a diol, a linear polyether can be made. Such a reaction isshown in Equation (1) below: ##STR12## Suitable diols include ethyleneglycol, diethylene glycol, triethylene glycol, tetraethylene glycol,other higher polyethylene glycols, propylene glycol, dipropylene glycol,tripropylene glycol, 2,2-dimethyl 1,3-propanediol, 1,4-butanediol,1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol,1,9-nonanediol, and 1,10-decanediol. Suitable aldehydes includeformaldehyde, paraformaldehyde, 1,3,5-trioxane, acetaldehyde and itstrimer, butyraldehyde and its trimer, pentanal, hexanal, 2-ethylbutanal, chloroacetaldehyde, dichloroacetaldehyde andtrichloroacetaldehyde.

An alternative means of preparing the same polymer involves the reactionof an acetal with a diol. The synthesis involves the initial preparationof an acetal by reaction of an alcohol with the aldehyde as shown inEquation (2) below:

    RCHO+2R'OH→(R'O).sub.2 C(R)H+H.sub.2 O              (2)

The acetal interchange is followed by a smoothly reversible reaction inacid media giving rise to the polyacetal. This reaction is given inEquation (3) below:

    (R'O).sub.2 C(R)H+HO(CH.sub.2).sub.n OH→HO[(CH.sub.2).sub.n OC(R)HO].sub.x H+2R'OH                                    (3)

Suitable acetals include the diethyl, dipropyl, dibutyl, dipentyl anddiphenyl acetals of all of the previously mentioned aldehydes.

A well known reaction which is particularly well suited for preparingcopolymers of acetaldehyde involves the reaction of divinyl ethers withdiols. For example, ethylene glycol divinyl ether will react withethylene glycol in the presence of H⁺ at -10° C. to give a 1:1 copolymerof ethylene glycol and acetaldehyde. Similarly, the divinyl ether of1,5-pentanediol will react with 1,5-pentanediol to give a copolymer ofpentanediol and acetaldehyde: ##STR13## Terpolymers can be prepared byreacting a divinyl ether of one diol with a diol of a differentstructure. For example, the divinyl ether of ethylene glycol will reactwith 1,3-propanediol to yield a polyether after fluorination having thefollowing structure: ##STR14## The divinyl ethers are convenientlyformed by reacting a dihydroxyl terminated compound with acetylene at160° C. in the presence of KOH as shown below in Equation (5). ##STR15##

A variety of aldehydes can be polymerized and fluorinated to giveperfluoropolyethers that have unique and often useful properties. Forexample, chloroacetaldehyde can be polymerized and fluorinated to giveperfluoropolychloroacetaldehyde. Similarly, dichloroacetaldehyde andtrichloroacetaldehyde can be polymerized and fluorinated to give theperfluorocarbon analog of the polyethers. Chlorofluoroethers such asthese are potentially useful nonflammable aircraft hydraulic fluids.Their relatively high oxidative stability and low compressibility makethem attractive candidates. Other aldehydes such as acetaldehyde,trifluoroacetaldehyde and propanal can be polymerized and fluorinated togive stable polymers.

Ketals undergo a facile reversible metathesis reaction with alcohols togive polyketals as shown below in Equation (4):

    (R'O).sub.2 C(R)R"+HO(CH.sub.2).sub.n OH→HO[(CH.sub.2).sub.n OC(R)(R")O].sub.X H+2R'OH                                 (6)

The list of useful ketals would include 2,2-dimethoxypropane,2,2-dimethoxybutane, 2,2-dimethoxypentane, 2,2-dimethoxyhexane,3,3-dimethoxypentane, 3,3-dimethoxyhexane as well as the diethoxy,dipropoxy, dibutoxy and diphenoxy analogues of the previously mentionedketals.

The direct reaction of a ketone with an alcohol, a reaction analogous tothe reaction of an aldehyde with an alcohol, generally works only forseveral isolated ketones. For this reason, the ketal is normally used.

The reaction of a trialkyl or triaryl orthoester with alcohols givesformates according to the reaction presented in Formula (5): ##STR16##Useful orthoesters include trimethylorthoformate, triethylorthoformate,tripropylorthoformate, tributylorthoformate, triphenylorthoformate,trimethylorthoacetate, triethylorthoacetate, tripropylorthoacetate,tributylorthoacetate, triphenylorthoacetate, trimethylorthopropionate,triethylorthopropionate, tripropylorthopropionate,tributylorthopropionate, triphenylorthopropionate,trimethylorthobutyrate, triethylorthobutyrate, tripropylorthobutyrate,tributylorthobutyrate and triphenylorthobutyrate.

It should be clear from the preceding discussions that a wide variety oflinear as well as highly branched polyethers can be made using theseinterchange reactions. By carefully choosing the appropriate diol andaldehyde it is possible to prepare cyclic acetals which can often bepolymerized to give polyethers. For example, formaldehyde reacts withdiethylene glycol to give 1,3,6-trioxocane which can be polymerized togive linear polyacetals as shown in Formula (6) below: ##STR17##Similarly, the cyclic products formed by the reaction of trimethyleneglycol with dibutyl formal and the reaction of hexamethylene glycol withpropionaldehyde polymerize in the presence of an acid to given linearpolymers as described in U.S. Pat. No. 2,071,252. In general, if theglycol is 1,4-butanediol or higher a linear polymer is formed whereasglycols having fewer carbons generally form rings. If the glycol used isa polyether glycol, such as diethylene glycol or triethylene glycol, thelinear polymer represents a thermodynamically more stable structure.However, it is often possible to convert the linear polyether to thecyclic ether by vacuum pyrolysis.

Conversion of the hydrocarbon polyether to a perfluoropolyether can beaccomplished by reacting the polyether with elemental fluorine. Becauseof the reactive nature of elemental fluorine, it is preferably to dilutethe fluorine with an inert gas such as nitrogen or helium. Typically,the fluorine is diluted with nitrogen and as higher degrees offluorination are achieved, the concentration of fluorine is usuallyincreased. Due to the extreme exothermicity of the reaction, thefluorination must be carried out slowly unless provisions have been madefor rapidly removing the heat of reaction. Submersion of the reactor ina cooled liquid bath is usually adequate for achieving commerciallyacceptable rates of reaction.

Fluorine gas is the preferred fluorinating agent and is commerciallyavailable at sufficiently high purity levels and at an acceptable cost.The fluorination reaction is generally carried out at a temperaturebetween -40° and +150° C., preferably between -10° and +50° C. It can becarried out in a reactor containing an ultraviolet radiation source orin the dark. Using the preferred temperature range, it is not necessaryto have an ultraviolet light source since the fluorine is sufficientlyreactive. If an ultraviolet light source is used, however, a wavelengthbetween 250 and 350 nm is preferred. When the reactor is irradiated withan external light source, a transparent window is needed which does notreact with either fluorine or hydrogen fluoride. A quartz lens coatedwith a thin film of fluorinated ethylene-propylene copolymer works well.

The fluorination reaction can be carried out in a variety of ways. Thepolyether can be coated on sodium fluoride powder to give a free-flowingpowder which can be fluorinated in either a stationary tube, in arotating drum type reactor, or in a fluidized bed. See U.S. Pat. No.4,755,567 and U.S. application Ser. No. 07/198,154, filed May 24, 1988,the teachings of which are incorporated herein by reference.

Alternatively, the polyether, if soluble, can be dissolved in a solventinert to fluorine and can be fluorinated while in solution using aliquid phase fluorination reactor. See U.S. patent application Ser. No.07/250,376, entitled "Liquid Phase Fluorination", by Thomas R.Bierschenk, Timothy Juhlke, Hajimu Kawa and Richard J. Lagow, filedSept. 28, 1988, and U.S. Ser. No. 07/414,119, entitled "Liquid PhaseFluorination", filed concurrently herewith, the teachings of each areincorporated by reference herein. A typical laboratory-size reactor forexample, has a volume of about 10 liters and contains approximately 2 to8 liters of a suitable solvent. Perhalogenated chlorofluorocarbons aretypically used as the fluorine inert fluorination medium. However,perfluorocarbons, such as Fluorinert™ FC75 [3M Corporation; mixture ofperfluoro(2-butyltetrahydrofuran) andperfluoro(2-n-propyltetrahydropyran)] and perhalogenatedchlorofluoropolyethers may also be used as the liquid phase fluorinationmedium. One preferred fluorination medium is1,1,2-trichlorotrifluoroethane since it does not react appreciably withfluorine when the preferred temperature range is used (above the meltingpoint of the material and below the temperature at which the fluorinereacts with it). Other fluorinated solvents can be used, such asperfluoroamines, perfluoroalkanes, low molecular weight polyethers, etc.

During a typical reaction, the polyether is fed into the reactor at arate of 10 to 60 grams per hour. Fluorine gas is delivered to thevigorously stirred reactor at a rate sufficient to react with all of theorganic feed plus an additional 5 to 10 percent. Typically the fluorinegas is diluted with an inert gas such as nitrogen. This is of particularimportance if a liquid fluorination medium such as1,1,2-trichlorotrifluoroethane is used. It is imperative to keep thefluorine concentration low so that the liquid fluorination medium andfluorine in the vapor space do not form a flammable mixture. Theflammability limits of various solvents in fluorine gas can bedetermined by spark testing. In a typical reaction, a fluorineconcentration of 10 to 40% works well. If operating properly, thefluorine concentration in the exit gas will be between 2 and 4%.

Fluorination can be carried out either in a batch mode where all of thepolyether is dissolved in a solvent prior to fluorination or in acontinuous mode where the polyether is continuously being pumped intothe solvent as fluorine is being bubbled through the solution. Generallyspeaking, the continuous operation gives a preferred yield, betterproduct quality and improved rates.

If the polyether is insoluble in the liquid fluorination medium it canstill be fluorinated in high yield as an emulsion in the liquid phasereactor. An emulsified solution of the polyether and the fluorine-inertliquid fluorination medium can either be pumped into the reactor or thereactant can be emulsified in the reactor with the fluorination mediumprior to the reaction.

An alternative method for fluorinating polyethers which are insoluble inthe liquid fluorination medium involves adding a solvent to thepolyether which allows limited solubility of polyether in the liquidfluorination medium. For clarity, 1,1,2-trichlorotrifluoroethane hasbeen selected as the liquid fluorination medium; however, other highlyfluorinated solvents can also be used. Typically, a mixture containingone part polyether, one part solvent and one part1,1,2-trichlorotrifluoroethane will give a homogeneous solution. Asolvent is selected which readily dissolves the polyether. Often it ispossible to choose a solvent which will consume little, if any, of thefluorine gas. Trifluoroacetic anhydride, trifluoroacetic acid,chloroform, 1,1,2-trichloroethylene and 1,1,2-trichloroethane workespecially well and have high solvating power.

The polyether/solvent/1,1,2-trichlorotrifluoroethane solution is meteredinto a vigorously stirred fluorination reactor. As the polyethersolution contacts the 1,1,2-trichlorotrifluoroethane in the reactor, anemulsion is formed. The polyether droplets in the solution are in mostcases sufficiently small and react quickly with the fluorine gas withnegligible side reactions.

When carrying out the reaction in a liquid fluorination medium, ahydrogen fluoride scavenger such as sodium fluoride or potassiumfluoride may or may not be present in the solution to scavenge theby-product hydrogen fluoride. However, the preferred mode of carryingout the fluorination reaction is with a sufficient quantity of sodiumfluoride being present to complex with all of the hydrogen fluorideformed. When fluorinating ethers in the presence of sodium fluoride,improved yields are obtained while chain cleavage and rearrangements areminimized. See U.S. Pat. No. 4,755,567, the teachings of which areincorporated herein by reference.

Products produced using the methods just described usually have aresidual hydrogen content of 0.001% or less. In order to obtain a fluidwhich is essentially free of residual hydrogen and void of any reactiveterminal groups such as acyl fluoride groups resulting from chaindegradation reactions, a final fluorination near 175° C. with 30%fluorine for several hours works well.

The following examples will further illustrate the invention, but arenot to be construed as limiting its scope.

EXAMPLE 1

A mixture of 1060 g diethylene glycol (10 mol), 210 g paraformaldehyde(7 mol), 500 ml benzene and 10 g acidic ion exchange resin was refluxedfor 6 hours in a 2 liter flask equipped with a water separator and areflux condenser. The solution was filtered to remove the acid catalystand the benzene was removed by distillation. Upon removal of all of thebenzene, several drops of sulfuric acid were added to the polymer andthe temperature was raised to approximately 140° C. The entire contentsof the flask were distilled at 160° C. with a reduced pressure (25 mm).Redistillation of the high boiling fraction gave 463 grams of 1,3,6trioxocane (78% conversion).

Polymerization of 450 g of 1,3,6-trioxocane was carried out at roomtemperature in 1 liter dry methylene chloride using 0.04 ml oftrifluoromethane sulfonic acid as a catalyst. The polymerization wascomplete in 24 hours at which time 1 g of sodium methoxide dissolved in50 ml of dry methanol was added to neutralize the acid catalyst. 3600 gsodium fluoride powder was added to the polymer along with an additional1 liter of methylene chloride. The mixture was stirred, the methylenechloride was allowed to evaporate and the remaining solids were groundto a powder. The polymer-coated sodium fluoride was placed in a 20 literrotating drum reactor and dried under a stream of inert gas (e.g.,nitrogen) for a period of 12 hours. The mixture was then exposed to 500cc fluorine diluted with 2 liters of nitrogen for approximately 30 hoursat 25° C. Next, the nitrogen flow was reduced to 1 liter/min and thereaction was allowed to continue for an additional 12 hours after whichtime the reactor was slowly warmed to 70° C. over a 6 hour period.Treatment with pure fluorine for several hours at 70° C. gave a productwhich contained very few hydrogen atoms. Extraction of the reactionproduct with 5 liters of 1,1,2-trichlorotrifluoroethane gave 386 gramsof fluid (34%). Washing of the solids with 100 liters of water resultedin the isolation of 430 grams of an elastomeric solid (38% yield). Thecrude fluid was treated with 30% fluorine at 260° C. for 12 hours toremove the last remaining hydrogens. The fluid was distilled to give thefollowing fractions:

    ______________________________________                                                                         Kinematic                                    b.p.         Weight              Viscosity (cst.)                             range (°C.)                                                                         fraction (g)                                                                            % of total                                                                              20° C.                                                                       80° C.                          ______________________________________                                        <200° C. at 100 mm                                                                  120       31         3.2  1.07                                   >200° C. at 100 mm                                                                  126       33        11.8  2.83                                   <245° C. at 10 mm                                                      >245° C. at 10 mm                                                                   62        16        38.9  7.06                                   <288° C. at 0.05 mm                                                    >288° C. at 0.05 mm                                                                 39        10        83.3  13.1                                   <370° C. at 0.05 mm                                                    >370° C. at 0.05 mm                                                                 39        10        290.3 39.5                                   ______________________________________                                         The .sup.19 F data and elemental analysis were consistent with the            structure:                                                                    [CF.sub.2 CF.sub.2 OCF.sub.2 CH.sub.2 OCF.sub.2 O].sub.n                 

EXAMPLE 2

In this example the fluid prepared in Example 1 was prepared using analternate method which was better suited for preparing fluids while themethod described in Example 1 yields a considerable amount of polymericsolids.

Into a 1 liter stirred flask equipped with a water separator were placed500 g diethylene glycol (4.7 mol), 90 g diethylene glycol methyl ether(10.75 mol), 225 g paraformaldehyde (7.5 mol), 150 ml toluene and 5 gion exchange resin (H⁺ form) The mixture was refluxed for several hoursto remove the water formed during the reaction. The solution was firstfiltered to remove the ion exchange resin, then distilled to 150° C. at0.05 mm/Hg to remove the toluene and other lights. A nearly quantitativeyield of polymer having an average molecular weight of 1500 wasobtained.

320 g of polymer, mixed with 170 g chloroform and 300 g1,1,2-trichlorotrifluoroethane were slowly pumped over a 23 hour periodinto a 15 liter stirred fluorination reactor containing 6 liters of1,1,2-trichlorotrifluoroethane and 1300 g of sodium fluoride powder. 20%fluorine was bubbled through the liquid fluorination medium at a rate15% higher than that required to theoretically replace all of thehydrogen on the hydrocarbon being pumped into the reactor. The reactortemperature was maintained between 0° and +10° C. throughout thereaction. Following the reaction, the reactor contents were filtered andthe liquid fluorination medium (1, 1, 2-trichlorotrifluoroethane) wasremoved from the filtrate via an atmospheric distillation to 120° C. togive 535 g of crude fluid (66%). Fluorination of the fluid at 260° C.gave a clear, colorless fluid which was shown by elemental analysis and¹⁹ F NMR to have the following structure:

    [CF.sub.2 CF.sub.2 OCF.sub.2 CF.sub.2 OCF.sub.2 O].sub.n

EXAMPLE 3

100 g triethylene glycol (0.67 mol), 28.5 g paraformaldehyde (0.95 mol),100 ml benzene and 1 g ion exchange resin (H⁺ form) were placed in a 500ml stirred flask equipped with a water separator and a reflux condensed.The solution was allowed to reflux for 6 hours while the water wascontinuously removed. Upon removal of the water, the solution wasfiltered to remove the acid catalyst. Atmospheric distillation of thefiltrate followed by a reduced pressure distillation (100 mm Hg) to 120°C. was used to remove the benzene solvent as well as any lights present.

Twenty grams of the viscous polymer were mixed with approximately 100 mlof methylene chloride and 120 g sodium fluoride powder (200 mesh). Theresulting paste was dried in a vacuum oven at 60° C. for several hoursprior to grinding to a coarse powder (approximately 30 mesh). The powderwas placed in a 1 liter rotating brass reactor and was purged with 200cc of dry nitrogen for several hours prior to the fluorination. Thereactor was cooled to 0° C., the nitrogen flow was reduced to 150 cc/minand the fluorine flow was set at 20 cc/min. These conditions weremaintained for approximately 30 hours after which time the nitrogen flowwas reduced to 100 cc/min and the reactor was allowed to slowly warm to45° C. over a 4 hour period. Next, the nitrogen flow was turned off andthe reactor was slowly warmed to 70° C. over a 3 hour period. Uponheating to 70° C., the polymer was exposed to pure fluorine for anadditional hour. Extraction of the sodium fluoride/polymer mixture withapproximately 1 liter of 1,1,2-trichlorotrifluoroethane gave 23 g offluid (45% yield) having the following structure which has beenconfirmed spectroscopically:

    [CF.sub.2 CF.sub.2 OCF.sub.2 CF.sub.2 OCF.sub.2 CF.sub.2 OCF.sub.2 O].sub.n

EXAMPLE 4

400 g tetraethylene glycol (2.06 mol), 109 g paraformaldehyde (3.62mol), 17 g triethylene glycol methyl ether (0.103 mol), 150 ml benzeneand 5 g ion exchange resin were allowed to react in a 1 liter flaskcontaining a water separator. After 6 hours, the contents of the flaskwere filtered and the lights were removed via a vacuum filtration. A 265g sample of the polymer was mixed with 160 g chloroform and 285 g1,1,2-trichlorotrifluoroethane. The polymeric solution was metered, overa 22 hour period, into a stirred 10 liter fluorination reactor whichcontained 1150 g sodium fluoride powder and 4.5 liters of1,1,2-trichlorotrifluoroethane. The reactor was maintained at 7° C.while 20% fluorine (diluted with nitrogen) was metered into the reactorat a rate sufficient to react with all of the organic entering thereactor. Upon completion of the reaction, the solution was filtered andthe liquid fluorination medium was removed via a distillation yielding422 g (62% yield) of a clear, stable fluid. The product was fractionatedinto three samples, one which boiled below 200° C. at 0.05 mm Hg (40%),a second which boiled between 200° and 300° C. at 0.05 mm (35%) and athird having a boiling point above 300° C. at 0.05 mm Hg (25%). Theintermediate fraction had a viscosity of 33.1 cst. at 20°, 6.3 cst. at80° and 2.13 cst. at 150° C. The pour point was -79° C. The analysis wasconsistent with the formula:

    [CF.sub.2 CF.sub.2 OCF.sub.2 CF.sub.2 OCF.sub.2 CF.sub.2 OCF.sub.2 CF.sub.2 OCF.sub.2 O].sub.n

¹⁹ F NMR (δ ppm vs CFCl₁₃); -51.8:CF₂ O; -56.0:CF₃ O; -88.8, -90.6:CF₂CF₂ O. Anal. Calcd. for C₉ F₁₈ O₅ : 20.4, C; 64.5, F. Found 21.0, C;65.1, F.

EXAMPLE 5

A mixture of 400 g dipropylene glycol (3.0 mol), 358 g paraformaldehyde(12 mol), 150 ml toluene and 10 g ion exchange resin was refluxed for 5hours in a stirred 1 liter flask equipped with a water separator. Theion exchange resin was removed prior to distillation of the mixture to150° C. under a full vacuum to remove any low molecular weight polymer.Approximately 200 g of polymer remained in the flask which was shown bygel permeation chromatography to have an average molecular weight ofapproximately 3000.

The polymer (280 g) was mixed with 340 ml 1,1,2-trichlorotrifluoroethaneand was slowly pumped into a 15 liter stirred reactor over a 24 hourperiod. The reactor, which contained 5.5 liters of1,1,2-trichlorotrifluoroethane and 1220 g sodium fluoride powder, wasmaintained at 10° C. throughout the reaction while 20% fluorine wasbubbled through the liquid fluorination medium at a rate just exceedingthat required to react with all of the starting material being pumpedinto the reactor. The reactor contents were filtered and distilled togive 587 g of fluid which was further treated with 50% fluorine at 270°C. to give a fluid which was essentially free of hydrogen. The purifiedproduct was fractionated into three samples. The first fraction boiledbelow 200° C. at 0.05 mm Hg, the second distilled over between 200° and300° C. at 0.05 mm and the distillation bottoms had a boiling pointabove 300° C. at 0.05 mm Hg. The second fraction comprised approximately20% of the total fluid with the majority of the sample having a boilingpoint below 200° C. at 0.05 mm.

The viscosity of the second fraction at 20° C. was 72.2 cst. (ASTM slopeof 0.644). The pour point was -62° C.

¹⁹ F NMR (δ ppm vs CFCl₃):-47.3,-49.3,-51.4:CF₂ O; -54.0, -55.8:CF₃O;-79.7:OCF(CF₃)CF₂ O;-81.8,-82.8, -84.7:OCF(CF₃)CF₂ O;-87.3:CF₃ CF₂O;-130.0:CF₃ CF₂ O; -140.3,-144.8,-146.0:OCF₂ CF(CF₃)O.

Anal. Calcd. for CF₃ O[CF₂ CF(CF₃)OCF₂ CF(CF₃)OCF₂ O]_(n) CF₂ CF₃ : C,21.02; F, 67.02. Found. C, 21.08; F, 67.08.

EXAMPLE 6

Using techniques similar to those described in the previous examples,350 g 1,4 butanediol, 43 g n-propanol and 200 g paraformaldehyde werereacted in benzene to give a fluid which was treated with 85 g aceticanhydride to give 325 g of a polymeric material having a viscosity of162 cst. at 30° C. Fluorination of 305 g of the fluid in a typical 40°C. fluorination reaction gave 577 g of fluid of which approximately 30%boiled between 200° and 300° C. at 0.05 mm/Hg.

¹⁹ F NMR (δ ppm vs CFCl₃):-51.7(f), -82.1(a), -85.4(d), -86.5(c),-125.9(e) and -130.3(b). ##STR18##

EXAMPLE 7

lnto a 1 liter stirred flask were placed 350 g 1,5 pentanediol (3.4mol), 23 g n-butanol (0.3 mol), 175 g paraformaldehyde (5.8 mol) and 200ml benzene. Upon refluxing the mixture for approximately 3 hours with anacid catalyst present, 390 g of a polymeric fluid was obtained which hada viscosity of 450 cst. at 100° F. Fluorination of 310 g of the fluid ina typical fluorination reaction at 14° C. gave 708 g of fluid (80%yield) of which approximately 30% boiled between 200° and 300° C. at0.05 mm Hg.

¹⁹ F NMR (δ ppm vs CFCl₃)-51.3(g), -55.7(c), -81.7(a), -85.0(d),-122.3(f), -125.5(e) and -126.7(b). ##STR19##

EXAMPLE 8

Using techniques similar to those described in the previous examples,350 g 1,6-hexanediol (3.0 mol) 49.3 g n-pentanol (0.56 mol), 134 gparaformaldehyde (4.46 mol) were reacted in benzene to give 425 g of apolymeric material having a viscosity of 600 cst. at 100° F.Fluorination of 628 g of the fluid in a typical reaction at 10° C. gave628 g of fluid (71% yield), of which approximately 30% boiled between200° and 300° C. at 0.05 mm Hg.

¹⁹ F NMR (δ ppm vs CFCl₃):-51.3(i), -56.0(b), -81.7(a), -85.0(f),-85.3(e), -122.7(h), -123.0(c), -125.5(g) and -126.3(d). ##STR20##

EXAMPLE 9

Into a 500 ml flask were placed 100 g diethylene glycol (0.94 mol), 55.7g acetaldehyde diethyl acetal (0.47 mol), 200 ml benzene and 2.5 gacidic ion exchange resin. Attached to the flask was an apparatusdesigned to continuously extract the by-product ethanol from therefluxing benzene. After approximately 6 hours, the refluxing benzenewas essentially free of ethanol and the reaction was assumed to becomplete. Filtration of the crude reaction product gave a solution freeof the ion exchange resin. Removal of the benzene was accomplished usinga rotary evaporator (70° C. bath with a nitrogen purge through thesolution).

20 grams of the polymeric product were mixed with 100 ml of methylenechloride and 120 g sodium fluoride powder. On drying the paste, 140 g ofa free flowing powder was obtained. Using the fluorination procedures ofExample 3, a 50% yield of the following fluorinated fluid was obtained:

    [CF.sub.2 CF.sub.2 OCF.sub.2 CF.sub.2 OCF(CF.sub.3)O].sub.n

¹⁹ F NMR (δ ppm vs CFCl₃): -56.0:CF₃ O;-86.3;OCF(CF₃)O;-87.3:CF₃ CF₂ O;-87.7:CF₃ CF₂ O;-88.7;OCF₂ CF₂ O;-96.3;OCF(CF₃)O.

EXAMPLE 10

Using the procedures detailed in the previous examples, 400 gtetraethylene glycol (2.06 mol) was reacted with 243.5 g acetaldehydediethyl acetal (2.06 mol) in 250 ml benzene to give 250 g of a polymericfluid upon refluxing for 6 hours. The polymeric liquid (350 g) wascoated on 3555 g of sodium fluoride and placed in a 22 liter rotatingdrum reactor. After purging for several hours, the reactor was cooled to10° C. and the fluorine and nitrogen flow rates were set at 350 cc/minand 2 liters/min, respectively. After 25 hours, the nitrogen flow wasdecreased to 1.5 liter/min. After an additional 14 hours, the nitrogenflow was further reduced to 1 liter/min and the reactor was allowed toslowly warm to 35° C. over a 4 hour period. Upon reaching 35° C., thenitrogen was turned off and the reactor was further warmed to 65° C.prior to terminating the fluorine flow. An oil (371 g) was extractedfrom the sodium fluoride with 1,1,2-trichlorotrifluoroethane which wasdetermined to have the following structure:

    [CF.sub.2 CF.sub.2 OCF.sub.2 CF.sub.2 OCF.sub.2 CF.sub.2 OCF.sub.2 CF.sub.2 OCF(CF.sub.3)O].sub.n

¹⁹ F NMR (δ ppm vs CFCl₃) -56.0:CF₃ O;-86.7:OCF(CF₃)O;-87.4:CF₃ CF₂ O;-80.0:CF₃ CF₂ O;-88.7:OCF₂ CF₂ O;-96.7:OCF(CF₃)O.

EXAMPLE 11

A mixture of 600 g 1,5-pentanediol and 30 g potassium hydroxide washeated to 160° C. in a 1 liter flask. Acetylene gas was bubbled throughthe solution as it was rapidly stirred. The reaction was stopped after40 hours and the product was washed with water and distilled to give an85% yield of pentanediol divinyl ether (b.p. 192° C.).

A 1 liter flask cooled to -12° C. was charged with 104 g pentanediol anda trace of methane sulfonic acid. To this solution was added 156 gpentanediol divinyl ether. The solution was stirred rapidly for 2 hours.Then slowly warmed to room temperature over a 6 hour period to give aviscous polymer having viscosity of 650 cst. at 100° F.

The product from the above reaction can be fluorinated in a liquid phasereactor containing 1,1,2-trichlorotrifluoroethane and a sufficientamount of fluorine to complex with all of the hydrogen fluoride formedduring the reaction. A perfluoropolyether having the following structureis obtained:

    CF.sub.3 CF.sub.2 CF.sub.2 CF.sub.2 O[CF.sub.2 CF.sub.2 CF.sub.2 CF.sub.2 CF.sub.2 OCF(CF.sub.3)O].sub.n CF.sub.2 CF.sub.2 CF.sub.2 CF.sub.3

EXAMPLE 12

Chloroacetaldehyde (50 to 55 wt % in water) was distilled to give afraction boiling between 87° and 92° C. A 3 liter stirred flaskcontaining 1281 g of the chloroacetaldehyde distillate was placed in aroom temperature water bath. While maintaining a temperature below 55°C., 500 ml of concentrated sulfuric acid was slowly added over a onehour period. The mixture was stirred for an additional 3 days at 53° C.,then allowed to separate into two phases. The lower phase, containingsulfuric acid, was removed with a separatory funnel while the upperphase was placed into a 3 liter flask equipped with a mechanicalstirrer. Concentrated sulfuric acid (200 ml) was carefully added to thesolution while the temperature was held below 60° C. with a water baththroughout the addition. The flask was held at 50° C. for an additional20 hours resulting in a viscous oil being formed. The polymeric productwas dissolved in 1 liter methylene chloride and the solution was washedwith water several times followed by a rinse with dilute sodiumbicarbonate solution. The organic phase was isolated, dried overmagnesium sulfate and concentrated to give a dark, viscous product (719g polychloroacetaldehyde). The product was dissolved in 450 g chloroformand 305 g 1,1,2-trichlorotrifluoroethane to give a solution which wasmetered over a 22 hour period into a 20° C. fluorination reactorcontaining 5.5 liters of 1,1,2-trichlorotrifluoroethane. Following thereaction, the solvent was removed leaving behind a fluid with thefollowing structure

    ______________________________________                                         ##STR21##                                                                    Temperature °F.                                                                        Viscosity (cst.)                                              ______________________________________                                        -65             1240                                                          100             2.53                                                          176             1.14                                                          ______________________________________                                    

EXAMPLE 13

A mixture of 392 g 1,4-cylcohexanedimethanol (2.72 mol), 140 gparaformaldehyde (4.7 mol), 200 ml benzene and 10 g of a H⁺ ion exchangeresin was refluxed for several hours in a flask containing a waterseparator. A nearly quantitative yield of a sticky solid was obtainedafter removal of the solvent by distillation.

Fluorination of 263 g of the polymer, diluted with 220 g chloroform and340 g 1,1,2 trichlorotrifluoroethane in a reactor (10° C.) containing4.8 liters 1,1,2-trichlorotrifluoroethane and 1300 g sodium fluoridepower, gave 440 g of a perfluoropolyether having the followingstructure: ##STR22##

EXAMPLE 14

Into a 1 liter flask were placed 350 g tetraethylene glycol (1.8 mol),300 ml benzene, and 10 g ion exchange resin. The mixture was refluxedfor 1 hour to remove any moisture present. To the mixture was added 200ml dimethoxypropane. The distillate was continuously removed over a2-hour period in 50 ml increments, which were extracted with water toremove the ethanol formed in the reaction. After drying, the distillatewas returned to the flask. An additional 200 ml dimethoxypropane wasadded and the distillate was collected, extracted, dried, and returnedto the flask for an additional 3 hours. Removal of the resin and solventyielded 410 g of a polymeric fluid having a viscosity of 560 cst. at 30°C.

Fluorination of 336 grams of the polyether in a 10° C. reactorcontaining 5 liters of 1,1,2-trichlorotrifluoroethane and 1420 g sodiumfluoride powder gave 642 g of a perfluoropolyether (69.8% yield).

¹⁹ F NMR: (δ ppm vs CFCl₃): -55.8(a), -76.3(e), -87.3(d), -88.6(c) and-90.5(b). ##STR23##

EXAMPLE 15

A mixture of 300 g pentanediol (2.88 mol), 450 gchloroacetaldehyde/water mixture having a boiling point between 87° and92° C. and 150 ml benzene was refluxed in a flask containing a waterseparator. Approximately 5 grams of an acidic ion exchange resin wasadded to catalyze the reaction. After refluxing for approximately fivehours the solution was filtered and the benzene was removed bydistillation to leave a residue (approximately 400 g) having a viscosityof 9,700 cst. at 100° F.

Fluorination of 318 g of the polymer, diluted with 235 g chloroform and375 g 1,1,2-trichlorotrifluoroethane, in a 12° C. reactor containing 5liters of 1,1,2-trichlorotrifluoroethane and 1200 g sodium fluoridepowder gave 623 g (84% yield) of the fluorinated polyether in a 22-hourreaction.

¹⁹ F NMR (δ ppm vs CFCl₃) -73.4(h), -74.3(c), -81.6(a), -82.3(d),-87.1(g), -122.1(f), -125.3(e) and -126.3(b). ##STR24##

Equivalents

Those skilled in the art will recognize or be able to ascertain using nomore than routine experimentation many equivalents to the specificembodiments of the invention described herein. Such equivalents areintended to be encompassed by the following claims:

What is claimed is:
 1. A perhalogenated polyether having an averageformula: ##STR25## wherein Y and Y' are the same or different and areselected from the group consisting of linear and branchedperfluoroalkylenes having at least 2 carbon atoms;perfluoroalkylenehypheratehereoxyalkylene andperfluoropoly(alkyleneoxyalkylene) each having alkylene groupscontaining at least two carbon atoms wherein in Y or Y' one or more ofthe fluorine atoms may be substituted by a halogen atom other thanfluorine; wherein X and Z are the same or different and are selectedfrom the group consisting of --(CF₂)_(r) COF, --(CF₂)_(r) OCF₃,--(CF₂)_(r) COOH and C_(r) F_(2r+1-q) Cl_(q), wherein r is an integerfrom 1 to 12 and q is an integer from 0 to 25; wherein R₁, R₂, R₃ and R₄are the same or different and are selected from the group consisting of--F, --Cl, --CF₂ Cl, --CFCl₂, --CCl₃, perfluoroalkyl of one to tencarbon atoms and perfluoroalkoxyalkyl of one to ten carbon atoms whereinone or more of the fluorine atoms may be substituted by a halogen atomother than fluorine; wherein n is an integer from 2 to 1,000; andwherein m is an integer from 0 to 1,000; provided that when R₁, R₂, R₃and R₄ together are F, then Y or Y' comprises an ethylene group havingat least one fluorine atom which is substituted by a halogen other thanfluorine.
 2. A perhalogenated polyether of claim 1, wherein Y and Y' areselected from the group consisting of --C₂ F₄ --; --C₃ F₆ --; --C₄ F₈--; --C₅ F₁₀ --; C₆ F₁₂ --; --CF₂ CF(CF₃)--; --CF₂ CF(C₂ F₅)--; and--CF₂ CF(CF₂ Cl)--.
 3. A perhalogenated polyether having an averageformula: ##STR26## wherein R₁, R₂, R₃, R₄, R₅ and R₆ are the same ordifferent and are selected from the group consisting of --F, --Cl, --CF₂Cl, --CFCl₂, --CCl₃, perfluoroalkyl of one to ten carbon atoms andperfluoroalkoxyalkyl of one to ten carbon atoms wherein one or more ofthe fluorine atoms may be substituted by a halogen atom other thanfluorine; wherein X and Z are the same or different and are selectedfrom the group consisting of --(CF₂)_(r) COF, --(CF₂)_(r) OCF₃,--(CF₂)_(r) COOH and C_(r) F_(2r+1-q) Cl_(q) wherein r is an integerfrom 1 to 12 and q is an integer from 0 to 25; wherein n is an integerfrom 2 to 1000; m is an integer from 0 to 1000; p and t are the same ordifferent and are integers from 1 to 50, provided that when p and t areone and R₁, R₂, R₃ and R₄ together are F, then R₅ or R₆ is a group otherthan fluorine.
 4. A perhalogenated polyether of claim 3, wherein m iszero; R₁, R₂, and R₅ are F and p is an integer between 2 and 50.